SACRAMENTO  Bills to pay for state fire prevention programs are starting to trickle into rural mailboxes across California just as parts of San Diego County and the state smolder.

The $150 per year fee was approved by lawmakers last year to help shore up dwindling Cal Fire budgets, but is expected to be challenged in court before too long.

In San Diego County, this fall owners should start receiving early advisories that the bills are on the way, followed later by the actual assessment. The state plans to send out 66,730 bills countywide.

That has San Diego County supervisors steaming. They have already passed a resolution opposing the collection and have authorized staff to explore legal options.

“This tax will be an absolute nightmare resulting in confusion and litigation,” Supervisor Dianne Jacob said.

Frustrated supervisors argue residents already pay general taxes for protection. Thousands also live within special districts that assess fees for fire defenses, and many others send donations for volunteer departments.

San Diego County also pays Cal Fire, the state’s fire protection agency, an extra $11.2 million a year to defend some 1.5 million acres of backcountry around the clock, all-year-long. That includes keeping eight stations open in the winter that Cal Fire otherwise would close. The contract also reimburses Cal Fire for training volunteers who staff 24 rural stations.

County-provided rough estimates indicate that slightly more than 65,000 of some 92,500 parcels have structures subject to the $150 fee. There is a $35 credit for those who already pay a special district assessment.

There is no definitive timetable for mailing notices to those in San Diego County with property located within the boundaries of a “state responsibility area,” or SRA, defended by Cal Fire. The initial warnings and then the actual bills are being sent county-by-county in alphabetical order because the state’s computer system cannot do a quick turnaround of some 840,000 addresses. Imperial County’s September 12 date is the last one identified on the official list.

Those who do receive the bills are being advised to pay it within 30 days or protest in writing to Cal Fire. (The mailings will outline the procedures.)

There will be no respite from the fee, unless it’s overturned by lawmakers or the courts. The current bill is for 2012. A new bill for 2013 is expected to be delivered in March. It’s supposed to raise $84 million annually.

In a recent opinion column. Cal Fire Chief Ken Pimlott defended the fee, arguing that residents will benefit from various prevention programs, including defensible space, education, firebreaks and arson investigations.

“What the new law addresses are the benefits those individuals in homes in the SRA receive that the rest of the state’s residents do not,” he wrote.

The notice that bills were on the way was pushed by George Runner, member of the Board of Equalization, the state agency charged with collecting the cash.

“We were convinced most people didn’t even know they were in a SRA,” said Runner, a Republican and former lawmaker.

The battle over fire fees has been long and messy. State-imposed parcel taxes have been tossed out by the courts and lawmakers balked at other efforts to charge fees on property insurance bills. Democrats have long sought charging rural residents, contending they get a free ride at Cal Fire’s expense.

Governor Jerry Brown called it the “beneficiary pays principle.”

Cal Fire’s general fund budget allocation, including an emergency account that can be tapped for wildfires, has been shrinking, according to state figures. It was $762.7 million in 2010-11; $700.2 million in 2011-12; and $649.7 million in 2012-13.

The fee legislation signed by Brown last year directed the California Department of Forestry and Fire Protection to develop a policy on who should pay how much. After several tries over several months, the board earlier this year settled on a $150 fee per structure,

The Howard Jarvis Taxpayers Association, among others, have vowed to challenge the fees in court once payments are submitted to the state.

Critics say the fee amounts to an illegal tax because it was not passed by a supermajority of lawmakers. Democrats who pushed it through on a majority vote counter that it is a legitimate fee for service, in this case fire prevention. Under the state’s convoluted tax law, the fee would demand a supermajority if it had ben earmarked for fire suppression. As a result, none of the money can be spent on ground crews and engines.

“There are fires in San Diego right now,” Runner said. “None of this money is going to go to put those fires out.”

State officials know they are walking a thin line. The first mailing prominently featured a firefighter in full gear spraying water on a timber stand engulfed in flames. The art work was later yanked because it misled recipients into thinking the money would be used to fight fires, Cal Fire officials acknowledged.

Lawmakers wrap up their session in two weeks, leaving little time for a last-ditch repeal campaign.

“If somebody has a funding source that makes sense for that repeal I’m open to it,” said Assembly Speaker John Perez, D-Los Angeles.